Apparatus, method and sensor for measuring gas concentration
View Patent ↗An apparatus, method and sensor for measuring gas concentration. The apparatus includes a sensing unit and a processing unit. The sensing unit includes a first selective water vapour-permeable membrane, a first working electrode and a second working electrode. The first selective water vapour-permeable membrane allows the first working electrode to be in contact with water molecules while to prevent this first working electrode from being in contact with the gas molecules to be measured. The first working electrode generates an electrical signal caused by change in relative humidity, the second working electrode generates a superimposed electrical signal caused by the change in relative humidity and the gas molecules to be measured, and the processing unit acquires concentration of the gas based on the electrical signal and the superimposed electrical signal.
1. An apparatus for measuring gas concentration, comprising:
a sensing device comprising a first selective water vapour-permeable membrane, a first working electrode and a second working electrode, wherein the first selective water vapour-permeable membrane is configured to allow the first working electrode to be in contact with water molecules but to prevent the first working electrode from being in contact with the gas molecules to be measured, the first working electrode is configured to generate an electrical signal that is caused by change in ambient relative humidity, and the second working electrode is configured to generate a superimposed electrical signal caused by both the change in ambient relative humidity and reaction of the gas molecules to be measured;
wherein the sensing device comprises a first sensor and a second sensor, the first sensor comprises the first working electrode, and the second sensor comprises the second working electrode, the first working electrode is in contact with an external environment through the sensing surface of the first sensor, and the second working electrode is in contact with the external environment through the sensing surface of the second sensor, wherein the first selective water vapour-permeable membrane is provided on the sensing surface of the first sensor or on the surface of the first working electrode; or
the sensing device comprises one sensor comprising the first working electrode and the second working electrode, the first working electrode and the second working electrode are in contact with the external environment through the sensing surface of the sensor, wherein the first selective water vapour-permeable membrane is provided on the surface of the first working electrode or the part of the sensing surface through which the first working electrode is in contact with the external environment;
wherein the first selective water vapour-permeable membrane is foldable in such a manner that, the first selective water vapour-permeable membrane when unfolded, covers the part of the sensing surface of said one sensor through which the second working electrode is in contact with the ambient air, and the first selective water vapour-permeable membrane when folded, does not cover the part of the sensing surface of said one sensor through which the second working electrode is in contact with the ambient air; and
a processor configured to acquire concentration of the gas to be measured based on the electrical signal caused by the change in ambient relative humidity and the superimposed electrical signal.
2. The apparatus for measuring gas concentration of claim 1 ,
wherein the first selective water vapour-permeable membrane is provided on the sensing surface of said one sensor and is configured to selectively cover the part of the sensing surface through which the second working electrode is in contact with the external environment; or
the sensing device further comprises a second selective water vapour-permeable membrane, the second selective water vapour-permeable membrane is detachably or movably provided on the part of the sensing surface through which the second working electrode of said one sensor is in contact with the external environment, to selectively cover the part of the sensing surface of the said one sensor; or
the sensing device further comprises a second selective water vapour-permeable membrane, the second selective water vapour-permeable membrane is detachably or movably provided on the surface of the second working electrode.
3. The apparatus for measuring gas concentration of claim 1 , wherein each of the first and second sensors further comprises at least one auxiliary electrode.
4. The apparatus for measuring gas concentration of claim 1 , wherein the processor is configured to acquire the concentration of the gas to be measured through the following equation:
[
P
]
(
t
)
=
(
W
2
(
t
)
-
b
×
A
2
(
t
)
-
c
)
s
;
or
the first sensor comprises a first auxiliary electrode, the second sensor comprises a second auxiliary electrode, and the processor is configured to acquire the concentration of the gas to be measured through the following equation:
[
P
]
(
t
)
=
(
W
2
(
t
)
-
α
×
W
1
(
t
)
-
b
×
(
A
2
(
t
)
-
A
1
(
t
)
)
-
c
)
s
;
in which, [P](t) represents the concentration of the gas to be measured, W 2 (t) represents a detected signal of the second working electrode, W 1 (t) represents a detected signal of the second auxiliary electrode, A 2 (t) represents a detected signal of the first working electrode, A 1 (t) represents a detected signal of the first auxiliary electrode, t represents time, and each of a, b, c and s represents an empirical coefficient to be calibrated.
5. The apparatus for measuring gas concentration of claim 1 , wherein each of the first and second sensors comprises one or two auxiliary electrodes, one or two reference electrodes and one or two counter electrodes; or each of the first and second sensors comprises one working electrode, one auxiliary electrode, one counter electrode and one reference electrode; or said one sensor comprises two working electrodes, one auxiliary electrode, two counter electrodes and one reference electrode.
6. A method for measuring gas concentration, applied to the apparatus for measuring gas concentration of claim 1 , wherein the method comprises:
acquiring an electrical signal caused by change in ambient relative humidity and a superimposed electrical signal caused by both the change in ambient relative humidity and the reaction of the gas molecules to be measured on the surface of the second working electrode; and
acquiring concentration of the gas to be measured based on the electrical signal and the superimposed electrical signal.
7. The method for measuring gas concentration of claim 6 ,
wherein the sensing device comprises the first sensor and the second sensor, the first sensor comprises the first working electrode, and the second sensor comprises the second working electrode, the first working electrode is in contact with an external environment through the sensing surface of the first sensor, and the second working electrode is in contact with the external environment through the sensing surface of the second sensor, wherein the first selective water vapour-permeable membrane is provided on the sensing surface of the first sensor or on the surface of the first working electrode, wherein the first sensor comprises a first auxiliary electrode, the second sensor comprises a second auxiliary electrode, the concentration of the gas to be measured is acquired based on the following equation:
[
P
]
(
t
)
=
(
W
2
(
t
)
-
b
×
A
2
(
t
)
-
c
)
s
;
or
the concentration of the gas to be measured is acquired based on the following equation:
[
P
]
(
t
)
=
(
W
2
(
t
)
-
α
×
W
1
(
t
)
-
b
×
(
A
2
(
t
)
-
A
1
(
t
)
)
-
c
)
s
;
in which, [P](t) represents the concentration of the gas to be measured, W 2 (t) represents a detected signal of the second working electrode, W 1 (t) represents a detected signal of the second auxiliary electrode, A 2 (t) represents a detected signal of the first working electrode, A 1 (t) represents a detected signal of the first auxiliary electrode, t represents time, and each of a, b, c and s represents an empirical coefficient to be calibrated.
8. A sensor for measuring gas concentration, comprising:
a sensor body; and
a first working electrode within the sensor body, which is in contact with an external environment through a sensing surface; and
a first selective water vapour-permeable membrane, which is applied on the sensing surface of the first working electrode and completely covers the sensing surface, to allow the first working electrode to only be in contact with water molecules in the ambient air whilst prevents the first working electrode from being in contact with gas molecules to be measured, to generate an electrical signal whose change is largely caused by change in ambient relative humidity; or
the first selective water vapour-permeable membrane is applied on the surface of the first working electrode, to allow the first working electrode to only be in contact with water molecules in the ambient air and prevent the first working electrode from being in contact with the gas molecules to be measured, to generate an electrical signal whose change is largely caused by the change in ambient relative humidity;
wherein the sensor further comprises a second working electrode inside the sensor body, the second working electrode is in contact with the external environment through the sensing surface;
wherein the first selective water vapour-permeable membrane is foldable in such a manner that, the first selective water vapour-permeable membrane when unfolded, covers the part of the sensing surface of said sensor through which the second working electrode is in contact with the ambient air, and the first selective water vapour-permeable membrane when folded, does not cover the part of the sensing surface of said sensor through which the second working electrode is in contact with the ambient air.
9. The sensor for measuring gas concentration of claim 8 , wherein
the first selective water vapour-permeable membrane is applied on the sensing surface and selectively cover or not cover the part of the sensing surface through which the second working electrode is in contact with the external environment; or
the sensor further comprises a second selective water vapour-permeable membrane, the second selective water vapour-permeable membrane is detachably or movably provided on the sensing surface through which the second working electrode is in contact with the external environment, to selectively cover or not cover the sensing surface; or
the sensor further comprises a second selective water vapour-permeable membrane which is detachably or movably provided on the surface of the second working electrode.
10. The sensor for measuring gas concentration of claim 8 , wherein the sensor further comprises at least one auxiliary electrode.